Erosion and sediment control plan

MMC - GAMUDA JV

MMC Corporation Berhad Gamuda Berhad

ENVIRONMENT ASIA SDN BHD MMC-GAMUDA JV SDN BHD

PROPOSED DOUBLE TRACKING RAILWAY PROJECT

BETWEEN IPOH - PADANG BESAR

MMC Corporation Berhad Gamuda Berhad

MMC - GAMUDA JV

The Project will involve the following works:

• Construction of new double track along new alignment

• Removal of the existing railway track, bridges and materials.

• Construction of new concrete bridges over rivers, streams and lakes for the new double track. Construction of new culverts.

• Construction of road over head bridges (ROB) to replace present level crossings.

• Construction of new stations and depots.

• Construction of Bukit Larut tunnel and Bukit Berapit Tunnel. • Fencing and electrification of the tracks.

Project Activities

MMC - GAMUDA JV

MMC Corporation Berhad Gamuda Berhad

ENVIRONMENT ASIA SDN BHD MMC-GAMUDA JV SDN BHD

Erosion and Sediment Control Plan

(ESCP)

• EROSION RISK ANALYSIS

• EROSION AND SEDIMENT CONTROL MEASURES

• MONITORING, SITE INSPECTION AND

• Erosion and sedimentation control measures under

Best Management Practices (BMPs)

EROSION & SEDIMENT CONTROL MEASURES

– Phasing of Construction Activities – Silt Traps

– Silt Fences

– Protection for Cut and Fill Slopes – Slope Stabilization of Embankments – Drainage Control

– Protection for Stockpiles – Vegetation Buffer

– Turfing

• Silt Trap

– to collect and store sediment

from areas cleared during

construction.

EROSION & SEDIMENT CONTROL MEASURES

Design of Silt Traps

Disturbed Area (x25m width)

Silt Trap Size (m) Length of

Track (m) Acre Hectare Width (W) Length (L) Depth (d) Type <500 3.09 1.25 12 24 2.5 A 500-1000 6.18 2.50 16 36 2.8 B 1000-1500 9.27 3.75 19 40 3.0 C >1500 12.36 5.00 22 45 3.0 D

Sizing for the Silt Traps (for Sandy Loam-Dry Sediment Basin)

Typical Design of Dry Sediment Basin Silt Trap

Sizing for the Silt Traps (for Clay Soil-Wet Sediment Basin)

Disturbed Area (x25m width)

Silt Trap Size (m) Length of

Track (m) Acre Hectare Width (W) Length (L) Depth (d) Type <500 3.09 1.25 12 24 2.5 A 500-1000 6.18 2.50 16 36 2.8 B 1000-1500 9.27 3.75 19 40 3.0 C >1500 12.36 5.00 22 45 3.0 D

Sizing for the Silt Traps (for Clay Soil-Wet Sediment Basin)

• Silt Fences

– to intercept drainage and surface flow prior to

entering nearby waterways or rivers.

– varying lengths of 50-100m depending on site

conditions and requirements.

EROSION & SEDIMENT CONTROL MEASURES

Typical Silt Fence

• Protection for Cut and Fill Slopes

EROSION & SEDIMENT CONTROL MEASURES

– Slopes above the railway platform will be cut according to the design specified by the geo-technical engineer and based on soil parameters to minimize erosion.

– temporary embankment should be well compacted to ensure that the soil particles are not readily eroded by runoff.

– The excess earth from cut activity, if any, should be stored temporarily at designated stockpile area.

– Fill areas should be compacted and graded so the runoff

diverts into the temporary drains, which leads to the silt traps. – The fill material should be compacted properly in order to

prevent excessive soil wash down during heavy rains. – Protection of borrow pit areas similar to cut and fill slopes. – All cut and filled slopes will be turfed.

• Slope Stabilization of Embankment

– Proposed methods : piled embankments and stone columns

EROSION & SEDIMENT CONTROL MEASURES

• Piled embankments - for ground improvement works and slope stabilization, mostly located at the slope area prior and after bridges.

• Stone columns - columns of compacted granular

material installed in soil for the purpose of improving the soil characteristics

• Drainage Control

– Before commencement of earthworks, temporary drains to be constructed to channel surface runoff for control of sediment discharge.

– Temporary drains should be directed into silt traps.

Sizing of Earth Drains

Earth Drain Size (m) Slope 1:2 Earth Drain Length (m) Width Depth <500 1.0 0.5 500 – 1000 1.0 1.0 1000 – 1500 1.5 1.0 >1500 1.5 1.5 Depth Width

• Protection for Stockpiles

EROSION & SEDIMENT CONTROL MEASURES

deposited in a designated depository area.

– Unsuitable material be temporarily stockpiled prior to being transported to designated dumpsites.

– Dumpsites / stockpiles should be located away from surface runoff flow paths and not adjacent to waterways.

– Stockpiles should be compacted, covered with plastic /

geotextile sheets that should be embedded into the top part of the stockpile or weighted down with heavy rocks.

• Vegetation Buffer

EROSION & SEDIMENT CONTROL MEASURES

– Site clearing shall be limited to work areas of the alignment for each stage of work.

– Vegetation cover should not be cleared until earthworks are ready to begin.

– Existing vegetation along the riverbanks should be

retained where possible as a natural buffer strip for the purpose of reducing runoff and increasing settling and infiltration.

– All cut and fill slopes will be turfed.

– main turfing carried out at sloping areas of the viaduct abutments.

– immediately upon completion of earthworks at exposed areas to reduce runoff velocity and to minimise erosion along contors.

– Vegetation that is fast growing and hardy is recommended.

EROSION & SEDIMENT CONTROL MEASURES

– Spot turfing and close turfing

techniques are recommended for entirely bare areas.

• Silt Curtain

– To be used at areas of land reclamation works.

– Constructed encircling the fill area to prevent excessive dispersal of sediments during the fill process.

EROSION & SEDIMENT CONTROL MEASURES

• Workers Camp, Site Offices, Casting Yard, Storage

Areas and Workshops.

EROSION & SEDIMENT CONTROL MEASURES

– Temporary internal drainage shall be constructed – Channel runoff effectively.

– All runoff should be channeled into a silt trap prior to discharge out of the site.

– The drainage system and the silt trap should be regularly inspected and maintained especially after heavy rainfall.

Oil Interceptor Silt Trap Wash trough Wash trough Legend Existing drainage Temporary drainage

MONITORING, SITE INSPECTION AND MAINTENANCE

Monitoring

• Total Suspended Solid (TSS)

• Contractor Activity BMP

• Sediment and Erosion Control BMPs

MONITORING, SITE INSPECTION

AND MAINTENANCE

MONITORING, SITE INSPECTION

AND MAINTENANCE

I)

Total Suspended Solid (TSS) Monitoring

• Monthly TSS Monitoring shall be carried out at all

discharge outlets of the silt traps during both the

earthworks and construction work.

• The water discharged from the silt traps should not

contain suspended solid load exceeding 100 mg/l as

stipulated by the DOE’s EIA Condition of Approval

No. 21.

MONITORING, SITE INSPECTION

AND MAINTENANCE

II) Contractor activity BMP Monitoring

 Inspect for evidence of spills requiring cleaning up activities.  Verify adequate supplies of spill containment and cleanup

materials (e.g. oil absorbent rolls/boom).

 Examine the integrity of containment structures.

 Verify employee education programs for the various activities.  Note the location of activity (e.g. outdoor vs. indoor, concrete

vs grass).

 Verify adequacy to provision of waste receptacles.

 Verify waste disposal practices (e.g. recycle vs. hazardous waste bins).

MONITORING, SITE INSPECTION

AND MAINTENANCE

III) Sediment and Erosion Control BMPs

• Monitor effectiveness of Sediment and Erosion Control BMPs.

• Sediment and Erosion Control BMPs may be ineffective if: – Silt is present outside the control area.

– Structural controls are breached or fail under storm events of minor intensity.

– Rills and gullies are present in stabilized slopes. – Silt buildup downstream of site.

– Controls are not maintained in accordance with design guidelines.

• Any change in drainage patterns and the extent of the change to be addressed accordingly.

MONITORING, SITE INSPECTION

AND MAINTENANCE

Site Inspection

• Regular site inspection to ensure the ESCP is always

operating in accordance with it’s design intent.

• The results of the inspection and assessment will be

recorded in writing.

• Frequency of Inspections:

– After any rain or storm event with substantial runoff (silt trap and silt fences).

– Daily when grass cover is less than 100% on vegetated areas.

– Weekly as a matter of site routine for all site practices. – Before site closure.

• Inspection of catch drains, earth banks, table drains, and slope drains. Initiate cleaning if required.

• Removal of any stockpile material or sediment that has encroached within 2 m distance to surface drain.

• Restoration of low spots in earth banks and diversion drains to their original height and compact.

• Where necessary, construction of extra earth drains and/or diversion drains that help separate on-site silted waters from other rain water runoff.

MONITORING, SITE INSPECTION

AND MAINTENANCE

Overall site inspection activities:

• Install any new erosion and sediment control measures that have become necessary since previous inspections due to severe storms or progress / changes in the site’s development. • Check to ensure that all earth banks, diversion drains, and

waterways are operating within the safe limits for the surface conditions by observing any scouring evidence.

• Ensure that any construction work at site since previous inspection has not diverted sediment and water away from planned runoff channels.

• Inspect structural integrity of silt traps and silt fences.

MONITORING, SITE INSPECTION

AND MAINTENANCE

Site Inspection

Maintenance Program

• Silt trap maintenance

• Silt fence maintenance

• Maintenance of vegetated surfaces

• Repairing of damaged and breached structures

MONITORING, SITE INSPECTION

AND MAINTENANCE

I) Silt trap maintenance

• When filled with sediment greater than 2/3’s of the depth, de-silting works to remove the accumulated sediment must be carried out immediately.

• The sediment should be removed for dumping at the approved dump site.

• All breaches of the gabion / bund wall must be repaired.

MONITORING, SITE INSPECTION

AND MAINTENANCE

Maintenance

Blocked riser Breach in bund wall

• Vegetative debris or construction waste material washed into the silt trap must be removed immediately to prevent blockage and damage to the bund wall or outlet pipe/riser.

MONITORING, SITE INSPECTION

AND MAINTENANCE

II) Silt fence maintenance

• Where the silt fence is being back-filled with accumulated sediment, these should be removed manually.

Maintenance

• The sediment should be removed for dumping at the approved dumpsite.

• All breaches of the silt fence must be repaired or replaced. • Vegetative debris or construction waste material washed

onto the silt fence must be removed to prevent any damage to the silt fence.

III) Maintenance of vegetated slopes

 Seek professional agricultural advice where necessary  Additional irrigation (watering)

 Application of fertilizers  Reseeding

 Mulching

 Weed control

MONITORING, SITE INSPECTION

AND MAINTENANCE

Maintenance

IV) Repairing of Damaged and Breached Structures

 Repair, re-pin, or replace torn detached and damaged liners, biodegradable blankets, geo-fabric.

 Fill and compact low spots in earth banks and diversion drains where vehicles or other factors have reduced the design height and stability.

Plan Review and Modifications

– The ESCP should be reviewed and modified if any changes significantly affect it were to occur such as:

• Changes to the Project schedule • Staging area modifications

• Off-site drainage impacts

• Repeated failures of designed controls.

• Properly installed systems are ineffective in preventing silt transport

off the site. This may be due to unforeseen site conditions or construction techniques.

• A new, relocated activity that could result in the discharge of

significant amounts of sediment.

– Changes should be identified accordingly, made known and the ESCP revised accordingly.

– During the preparation and review of the modified ESCP, construction work to continue with temporary modifications to the erosion and sediment control BMPs.

MONITORING, SITE INSPECTION

AND MAINTENANCE